Crawl-fins



Marc}! 1952 L. M. DE CQRLIEU 2,588,353

' CRAWLFINS Filed d'une 17, 1946 Patnted Mar. 11, 1952 UNITED STATES PATENT OFFICE Application June 17, 1946, Serial No. 677,256 In France June 19, 1945 6 Claims.

The present invention relates to a new equip ment for exercising the feet and toes cf swimmers, particularly children, so as to improve their legstroke especially when doing the crawl.

The bending crawl-fins in the form of flexible paddles for attachment to the foot, as described in U. S. A. Patent No. 2,099,973, artificially improve the propellant effect of the movements of the feet, but since they rest on the instep, they do not differntiate the toes from the rest of the foot, so that the toes are naturally much more stiff than normally. The improved equipment of the present invention, however, without undue limitation of its propellant properties, allows effective flexion of the feet and toes because it is fixed entirely to the toes instead of being a* tached simultaneously to the toes and the instep. 'Ihus full flexion of the feet is permitted, which exercises the toes and increases the suppleness of the toes relative to the foot, provided that the paddles are tightly held on the toes, and have a sufiiciently firm and. large surface. The paddles are so shaped that they widen progressively between the toes and the trailing edge so as to have maximum width at the trailing edge. Preferably in the region of this trailing edge beyond a firm and rigid main part cf the paddle, there is a flexible portion similar to that of the crawl-fins of the above quoted patent so as to improve the propellant properties. Nevertheless, although a flexible portion improves the propellant properties of the equipment, it is neither indispensable nor useful for exercising the feet particularly the joint between the toes and feet.

There are thus two principal types of this swimming equipment, (l) that which mainly exercises the feet, and (2) that which exercises and also propels. It is not possible to retain to the full the properties of the earlier crawl-fins in reducing fatigue and giving a high performance. Thes qualities must be sacrificed to some extent when deliberate exercise is required.

Supple foot movement is an important factor in the development of the leg stroke in the crawl. The role of this exercising equipment and of the propulsicn-exercising equipment, is primarily concerned With the training of children and youths from about 8 to 20.

Thus the present invention comprises equipment for exercising the feet and toes of swimmers, comprising a robust plate cf suitaole strength and dimensions, adapted to be attached firmly to the toes by suitable means 50 as to set as a prolongation Of the toes, and. te force them to bond in both directions under the pressure of water when the swimmer performs the leg stroke.

The attached drawing shows diagrammatically one form of the improved equipment of the present invention; in the drawing Figure 1 is a longitudinal vertical section of the equipment in use.

Figure 2 is a plan view of the same.

Figure 3 is a diagrammatic plan of the operative surface of a modification having a relatively good propulsion affect and constituting a combined propulsion-exercising equipment.

Figure 4 is a longitudinal elevation of a slightly modified form of the device shown in Figure 1, made in one piece.

As shown in Figures 1 and 2, the improved equipment consists essentially of a strong fiat paddle I made of any suitable material, such as metal, Celluloid, rhodoid, wood, ebonite, artificial resin or the like, properly stiif, and covered if desired by any suitable material or composition.

This paddle or operative surface l is firmly attached to a close-fitting pocket 2 for the toes.

To ensure that. the foot is firmly held within the combined paddle and toe-pocket, a band 3 which may be of elastic material or adjustable in length is fixed to the pocket in any suitable manner and passes behind the heel. In use this band should be tightly fastened.

The equipment is arranged and designed in such a way that the edge of the paddle member l bears exclusively on the toes, and not on the foot itself, so that such paddle member acts as an extension of the toes and forces them to bend to the full extent in both directions relative to the foot under the action of th water when the swimmer performs his leg stroke.

Since a swimmer naturally turns his foot slightly inwards, the inner edge of the paddle should follow the line of the foot, but the outer edge may usefully extend outwardly at an angle to the line of the foot, e. g. as shovvn in Figure 2.

The close-fitting pocket 2 is dispdsed around and under the toes which it encloses in such a way that the paddle l is firmly pressed against the toes. Thus this pocket should not stretch under the sole of the foot, and is limited by the length of the toes themselves, holding them firmly without stifness but without freedom of movement.

The apparatus is shown in the drawing with the paddle l arranged above the toes. It is equaliy possible to arrange it beneath the toes as a variation et the exerciser. Similarly, one can use a variation in which the toes are completely en- 3 closed above and beneath, as long as excessive stiffness is avoided.

T prevent the close fitting pocket 2 from gaping around the edge, elastic sections 4 and 5 may be provided both above and beneath the pocket so as to hold the edges thereof closely against the foot.

Finally a lining 6 of any suitable soit material may be placed in front of the toes in the inside of the close fitting pocket 2, so as to reduce rubbing on the front of the toes which are normally relatively sensitive. For example, this lining 6 may be made of cellular rubber, or any other suitable material, strengthened if desired, and may also contribute to the buoyancy of the equipment. In general, the close fitting pocket 2 may have any suitable shape so as to fit the toes and*hold them firmly, and one or the other of the closing sections 4 or 5 or both may, without undue inconvenience be dispensed With altogether.

Laces, adjustable straps and the like may alternatively be substituted for some or all of these fixing means as required, and it will readily be seen that considerable variation is possible without departing from the spirit of the invention.

Figure 3 shows in plan a modification of the paddle I of the apparatus, the remainder being essentially the same as in Figures 1 and 2. In this modification, which is a combined propulsion-exerciser equipment, the operative surface of the paddle which extends over and beyond the toes can be made of flexible and elastic material so as to improve the propulsive effect achieved by the apparatus, without essentially diminishing its exercising effect.

This operative surface may consist for example, of a plate i preferahly made of non-corrodible springy metal, such as hardened austenitic steel and shaped like a trident as shown in Figure 3, this plate being covered with a covering or flap 8 which conforms to the general overall shape shown. This shape may of course have a number of modifications in detail.

The plate 1 may have three fingers as in Figure 3, or any other desired number of fingers such as two, three, four or five. The base of the plate may advantageously be strengthened in any suitable manner for a sufiicient distance, and the trailing edge only should be very flexible, the base itself being long and strong.

This strong base may, if required, be made separately from its very flexible extension which may be attached to the base in any suitable manner. The metal plate 7, made in one or several pieces, may be so made as to have a progressively decreasing thicknss towards the trailing edge.

All of those desiderata, namely, the strength of the base, the elasticity of the flexible region near the trailing edge, and the progressive flexibility towards the trailing edge may be obtained equally well without a metal plate by using any suitable material, natural or synthetic or by making the equipment in one piece (Figure 4).

The equipment may be made entirely or largely of one substance such as rubber or any other similar material, natural or synthetic by moulding or any other process. Ridges or reinforcements of rubber or other material may be arranged either internally or externally, if required.

The region of the strong base may be made of ebonite or similar substance. Naturally a graded disposition of ridges or reinf0rcements could be employed, and the accompanying drawing shows equipment designed in accordance with normal engineering practice and not necessarily following the theoretically perfect shape. The general exterior shape of the apparatus should as far as possible be stream-lined, and should become thinner towards the trailing edge with or without reinforcements as required. Buoyancy may be achieved by the use of cellular rubber or other light material or by use of water-tight compartments.

The improvement in propulsion results partly from the fiexibility in the region of the trailing edge and in the reduction of eddies around the trailing edge, and partly by the increase of the operative surface of the paddle and of the spread of the trailing edge, as well as the continuity of impelling which of course is a well-known condition.

The general shape, details of construction, dimensions, fitting and materials may be varied without departing from the spirit of the invention, and those described here should be taken solely as examples.

What I claim is:

1. A propelling swim fin for attachment to the foot for exercising the feet of swimmers and more particularly for increasing the suppleness of the joints connecting the toes to the foot during the utilization thereof comp-rising a substantially rigid paddle portion constituting a prolongation of the foot, means defining a short, open-ended, close fitting toe receiving pocket at one end of said paddle portion, said end of the paddle por: tion extending within and longitudinally of said pocket substantially the length thereof, the bottom of the pocket being disposed inwardly of said end a distance such that the pocket accommodates only the toes of the user in juxtaposition to the paddle and fastening means connected to the pocket for passing behind the heel of the user to connect the fin to the foot after the toes have been inserted in the pocket so that utilization of the fin forces all the toes to simultaneously bend in both directions relative to the foot at the joints connecting the toes to the foot responsive to upward and downward movement of the leg in swimming.

2. A propelling swim fin for attachment to the foot for exercising the feet of swimmer5 and more particularly for increasing the suppleness of the joints connecting the toes to the foot during the utilization thereof comprising a substantially rigid paddle portion constituting a prolongation of the foot, means defining a short open-ended close fitting toe receiving pocket at one end of said paddle portion, said end of the paddle portion extending within and longitudinally of said pocket substantially the length thereof, the bottom of the pocket being disposed inwardl of said end a distance such that the pocket accommodates only the toes of the user in juxtaposition to the paddle, fastening means connected to the pocket for passing behind the heel of the user to connect the fin to the foot after the toes have been inserted in the pocket so that utilization of the fin forces all the toes to simultaneously bend in both directions relative to the foot at the joints connecting the toes to the foot responsive to upward and downward movement of the leg in swimming and elastic sections connected with and extending from the pocket in the direction away from the paddle a length such as to dispose such sections above and beneath the foot in the area immediately rearwardly cf the joints connecting the toes to the foot and said elastic sectiens terminating short of the instep area 01 the foot.

3. A swm fin as defined in and by claim 1 in which a short flexible extension s provided at the end of the paddle remote from the pocket tu improve the propellent properties of the fin.

4. A swm fin as defined in and by claim 1 in which the paddle is within and adjacent the upper surface of the pocket with the fin disposed horizontally so as to dispose the paddle in juxtaposition to the upper surface of the tees of the user.

5. A swim fin as defined in and by claim 1 in which the fastening means constitutes a flexible strap extendng from the pocket and of a length 15 such as to be passed'about the heel of the user to hold the fin to the foot.

6. A swim fin as defined in and by claim 1 in 6 which the paddle is of diverging width widening outwardIy of the pocket and includes a metal plate to provide the substantial rigidty.

LOUIS MARIE DE CORLE.

RFRENCES CITED '1he following references are of record in the file of this patent:

UN ITED STATES PATENTS Number Name Date 2,099,973 De Corfieu Nov. 23, 1937 2,321,009 Churchill June 8, 1943 2,343,468 Messinger Mar. 7, 1944 FOREIGN PATENTS Number Country Date 323,623 Italy Dec. 31, 1934 

